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Climate change doesn’t allow for time to evolve

July 14, 2013

“It is not just the dramatic nature of the [climate] changes that lie ahead – melting icecaps, rising sea levels and soaring temperatures – but the extraordinary speed at which they are occurring”.

This quote is from an Observer (Guardian) article by Robin McKie called “Climate change is happening too quickly for species to adapt“. The article discusses a new paper by evolutionary biologist Professor John Wiens of the University of Arizona. Here’s how McKie describes it:

“Using data from 540 living species, including amphibians, reptiles, birds and mammals, Wiens and colleagues compared their rates of evolution with the rates of climate change projected for the end of this century. The results, published online in the journal Ecology Letters, show that most land animals will not be able to evolve quickly enough to adapt to the dramatically warmer climate expected by 2100. Many species face extinction, as a result”.

Adaptation encompasses many strategies. The paper’s author makes the following point in the paper’s abstract: ”

…matching projected changes for 2100 would require rates of niche evolution that are > 10 000 times faster than rates typically observed among species…”

Niche evolution has a number of specific definitions, but a broad one would be the ability of a species to occupy a habitat that provides sufficient resources for the species to flourish.

The way the article reads, you might think the subject excluded humans, discussing ‘land animals’ – but we humans are also ‘land animals’. It isn’t made clear in this article that the same evolutionary principle applies equally to humans. Temperature adaptation is one example; some places may become too hot to live in, particularly if energy is too expensive to provide cooling, or where such amenities are simply unavailable in the first place. As the recent WMO report made clear, heat kills a lot more people than cold.

Agriculture is another key area where change will outstrip adaptation. When plants can no longer survive; when water supplies are insufficient to maintain a yield; where disease and predation increase as climate boundaries shift; these factors will put increasing pressure on agriculture even as the population continues to grow.

The article mentions the difficulties for some species of moving to a new territory, where they must compete for new resources. Humans cannot move; there’s no habitable place on the planet we don’t already occupy, and no spare planet. The reason the US military consider climate change a potential threat is, in part, because they anticipate forced movements of numerous peoples to places that don’t want them, and the inevitable conflict that will ensue.

The speed of climate change does not only threaten many species through an ability to make evolutionary adaptations. It threatens humans because, given the sheer numbers involved, we may be unable to adapt – and fund the economic costs of that adaptation – at a speed commensurate with the rate of change.

We daily plead with governments and institutions to act now, while we have time. I really don’t think many politicians realise just how fast that time is running out, not just for plants and animals, but for all of us.

One Comment leave one →
  1. August 6, 2013 6:48 am

    Another “footnote” – I’m aware of two mechanisms for rapid evolution (ie far more rapid than mutations in the genome). The first is mass culling where the only survivors are those with suitable traits for the new environment:

    The second is epigenetic mechanisms, where the genes are present in the genome but switched on or off as a result of stressors affecting the parents. Changes can thus rapidly manifest in as little as one generation, that in some instances may improve the ability of the offspring to cope.

    These two mechanisms provide at least some scope for rapid evolution (assuming you grant they are evolutionary mechanisms), although it doesn’t alter the bottom line alluded to in your article – which is that a lot of species simply aren’t going to make it.

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